我想通过操纵不透明度值在我的 GUI 上设置一个透明的控件。BackgroundWorker因此，我在我的 WPF-Form 的构造函数上初始化 a ，例如：
volumeWorker = new BackgroundWorker();
volumeWorker.DoWork += new DoWorkEventHandler(VolumeBarDoWork);
volumeWorker.ProgressChanged += new ProgressChangedEventHandler(VolumeBarChanged);
volumeWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(VolumeBarCompleted);
volumeWorker.WorkerReportsProgress = true;
之后，我的 GUI 等待一个由另一个类触发的事件
soundController = new SoundController();
soundController.VolumeChanged +=new SoundController.VolumeChangedEventHandler(VolumeChanged);
在事件处理程序上，我最终将启动 volumeWorker (BGW) 来操作 GUI：
private void VolumeChanged(float pVolume)
{
Logger.InfoWrite("Event raised ## New volume : {0}", pVolume);
volumeWorker.RunWorkerAsync();
}
但是在 BackgroundWorkers ChangeEvent 上，我每次都收到 InvalidOperationException。有人知道吗？
private void VolumeBarDoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
Logger.InfoWrite("Worker");
for(int _opacity = 99 ; _opacity >= 0 ; _opacity--)
{
Logger.InfoWrite("Start on {0}", _opacity);
worker.ReportProgress(_opacity);
System.Threading.Thread.Sleep(20)
}
e.Result = e.Argument;
}
private void VolumeBarChanged(object sender, ProgressChangedEventArgs e)
{
this.volumeBar.Opacity -= 0.01f;
Logger.InfoWrite("Changed opacity to : {0} on {1}", this.volumeBar.Opacity, e.ProgressPercentage);
}
private void VolumeBarCompleted(object sender, RunWorkerCompletedEventArgs e)
{
Logger.InfoWrite("Completed");
this.volumeBar.Opacity = 0.0f;
}